Embedded disconnected circuits in magnetic storage media of data storage devices

ABSTRACT

Disclosed herein are magnetic storage media with embedded disconnected circuits, and magnetic storage systems comprising such media. A magnetic storage media comprises a recording layer comprising a storage location, and an embedded disconnected circuit (EDC) configured to assist in at least one of writing to or reading from the storage location in response to a wireless activation signal. A magnetic storage system comprises a signal generator configured to generate a wireless activation signal, a magnetic storage media with a plurality of storage locations, and a write transducer and/or a read receiver. The magnetic storage media has at least one EDC configured to assist in writing to and/or reading from at least one of the plurality of storage locations in response to the wireless activation signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 16/018,360, filed Jun. 26, 2018 and entitled “EMBEDDED DISCONNECTEDCIRCUITS IN MAGNETIC STORAGE MEDIA OF DATA STORAGE DEVICES” (AttorneyDocket No. SDA-3214*A-US), which published on Dec. 28, 2018 as U.S.Patent Publication No. 20180373452. U.S. application Ser. No. 16/018,360claims priority to and incorporates by reference the contents of U.S.Provisional Application No. 62/525,272, filed Jun. 27, 2017 and entitled“EMBEDDED DISCONNECTED PASSIVE CIRCUITS IN DATA STORAGE DEVICES.”

This application hereby incorporates by reference for all purposes theentirety of the above-referenced U.S. application Ser. No. 16/018,360and U.S. Provisional Application No. 62/525,272. Additionally, as didU.S. application Ser. No. 16/018,360, this application herebyincorporates by reference for all purposes the entirety of the contentsof co-pending U.S. application Ser. No. 16/018,915, filed Jun. 26, 2018and entitled “METHODS OF USING EMBEDDED DISCONNECTED CIRCUITS INMAGNETIC STORAGE MEDIA OF DATA STORAGE DEVICES” (Attorney Docket No.SDA-3214*B-US), which published on Dec. 27, 2018 as U.S. PatentPublication No. 20180373453.

BACKGROUND

Data storage devices (such as, for example, disk drives) enable thestorage of large amounts of information in a small physical space. Asareal densities have increased, the sizes of write tracks and,therefore, write transducers have decreased accordingly. As aconsequence, the amount of flux generated by the write transducerdecreases, which means the head carrying the write transducer must flycloser to the surface of the disk in order to record data on the disk.As the head flies closer to the surface of the disk, which is notentirely smooth and/or may pick up particles that stick to its surface,the head can sometimes contact the disk, which may damage the head, thedisk, or both, or it may result in read or write errors.

Solid-state storage devices (SSDs) (i.e., devices that store dataelectrically rather than magnetically) provide arrays of storage cellsthat are addressable and do not require moving parts, such as a head tofly over the media to write and read data. SSDs require addressinglines, however, which reduce the amount of space on the device availablefor the storage of data.

There is, therefore, an ongoing need for improvements to data storagedevices.

SUMMARY

This summary represents non-limiting embodiments of the disclosure.

Disclosed herein are systems and methods using embedded disconnectedcircuits (EDC) within a data storage media and using the EDC to write toand read from the data storage media (e.g., a hard disk or other storagemedia). One or more components of an EDC are energized by anelectromagnetic field (of which there are many varieties, including, byway of example and not limitation, optical and radio waves) received byan antenna of the EDC. The energized EDC may be used to read and/orwrite data to storage locations of the media as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects, features, and advantages of the disclosure will be readilyapparent from the following description of certain embodiments taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates a hard disk drive that may embody one or moreembodiments disclosed herein.

FIG. 2A illustrates a cross-sectional view of an exemplary layered mediastack.

FIGS. 2B and 2C illustrate two possible arrangements of a recordinglayer of a magnetic recording media in accordance with some embodiments.

FIG. 2D illustrates a cross-sectional view of an exemplary media stackthat includes an EDC layer in accordance with some embodiments.

FIG. 2E illustrates an exemplary EDC layer in accordance with someembodiments.

FIG. 2F illustrates a cross-sectional view of another exemplary layeredmedia stack that includes an EDC layer in accordance with someembodiments.

FIG. 2G illustrates a cross-sectional view of another exemplary layeredmedia stack that includes an EDC layer in accordance with someembodiments.

FIGS. 3A-3C are simplified illustrations of exemplary magnetic storagesystems in accordance with some embodiments.

FIGS. 4A-4D illustrate certain elements of exemplary magnetic recordingsystems in accordance with some embodiments.

FIGS. 5A-5B are simplified illustrations of exemplary magnetic storagesystems in accordance with some embodiments.

FIGS. 6A-6D illustrate certain elements of exemplary magnetic recordingsystems in accordance with some embodiments.

FIGS. 7A-7G illustrate various exemplary embedded disconnected circuitsin accordance with some embodiments.

FIGS. 8A and 8B illustrate a magnetic storage system in accordance withsome embodiments.

FIG. 9 is a diagram illustrating an EDC in accordance with someembodiments.

FIG. 10 is a flowchart illustrating the process to read one or moreEDC-assisted storage locations using EDC in accordance with someembodiments.

FIG. 11 illustrates a process performed by an EDC to read one or moreEDC-assisted storage locations in accordance with some embodiments.

FIG. 12 illustrates the use of EDC in the context of reading from andwriting to a hard disk drive in accordance with some embodiments.

FIG. 13 illustrates an exemplary archival storage system in accordancewith some embodiments.

DETAILED DESCRIPTION

FIG. 1 illustrates several components of a hard disk drive 500. Themagnetic hard disk drive 500 includes a spindle 515 that supports androtates a magnetic disk 520. The spindle 515 is rotated by a spindlemotor (not shown) that is controlled by a motor controller (not shown)that may be implemented in electronics of the hard disk drive 500. Aslider 525, which is supported by a suspension and actuator arm 530,includes a combined read and write magnetic head 540. An actuator 535rotatably positions the suspension and actuator arm 530 over themagnetic disk 520. The components of the hard disk drive 500 may bemounted on a housing 545. It is to be understood that although FIG. 1illustrates a single disk 520, a single slider 525, a single head 540,and a single suspension and actuator arm 530, hard disk drive 500 mayinclude a plurality (i.e., more than one) of disks 520, sliders 525,heads 540, and suspension and actuator arms 530.

The slider 525 has a gas-bearing surface that faces the surface of thedisk 520 and counteracts a preload bias that pushes the slider towardthe disk 520. For convenience, in this document the gas-bearing surfaceis referred to as the air-bearing surface (ABS) and the gas is generallyreferred to as “air,” although it is to be understood that the gas usedin a hard disk drive 500 may be a gas other than air (e.g., the gas maybe helium). For simplicity, throughout this disclosure, the surface ofthe slider 525 that faces or that will eventually face the disk 520 isreferred to as the ABS.

As the disk 520 rotates, the disk 520 drags air under the slider 525 andalong the ABS in a direction approximately parallel to the tangentialvelocity of the disk 520. As the air passes under the ABS, aircompression along the air flow path causes the air pressure between thedisk 520 and the ABS to increase, which creates a hydrodynamic liftingforce that counteracts the tendency of the suspension and actuator arm530 to push the slider 525 toward the disk 520. The slider 525 thusflies above the disk 520 but in close proximity to the surface of thedisk 520.

In operation, the actuator 535 moves the suspension and actuator arm 530to position the slider 525 so that the magnetic head 540 is in atransducing relationship with the surface of the magnetic disk 520. Thehead 540 may be used to write information to one or more tracks on thesurface of the disk 520 and to read previously-recorded information fromthe tracks on the surface of the disk 520. Processing circuitry 510provides to the head 540 signals representing information to be writtento the disk 520 and receives from the head 540 signals representinginformation read from the disk 520. The processing circuitry 510 alsoprovides signals to the spindle motor to rotate the magnetic disk 520,and to the actuator 535 to move the slider 525 to various tracks.

For writing, the head 540 may use a single pole writer (i.e., a writetransducer) that has a main pole surrounded by magnetic shieldmaterials. The main pole is typically separated from the magnetic shieldmaterials by a non-magnetic spacer. The main pole may have a taperedshape with a tip that faces the magnetic recording media and is part ofthe ABS. The single pole writer may include a conductive coil encirclingthe writer pole in a helical or pancake-like configuration.

To write to the disk 520, the slider 525 passes over a region of thedisk 520, and an electric current is applied through the coil of thehead 540, which causes a large magnetic field to be generated from themain pole tip. The polarity of the generated field causes a region ofthe magnetic disk 520 to assume a polarity, thus enabling information tobe stored on the disk 520.

To read information from the disk 520, the head 540 may include only oneread sensor, or it may include multiple read sensors. The read sensor(s)in the head 540 may include, for example, one or more giantmagnetoresistance (GMR) sensors, tunneling magnetoresistance (TMR)sensors, or another type of magnetoresistive sensor. When the slider 525passes over a region of the disk 520, the head 540 detects changes inresistance due to magnetic field variations recorded on the disk 520,which represent the recorded bits.

Traditionally, the size of the bits has been reduced in order toincrease the amount of data that can be stored on the disk 520.Correspondingly, the size of the write transducer has decreased roughlyin proportion to the size of the bits. But to obtain high recordingdensity, a write field of sufficient magnitude must be focused on asmall area of the disk, which is increasingly difficult as the size ofthe write transducer decreases. Consequently, techniques such asmicrowave-assisted magnetic recording (MAMR) and heat-assisted magneticrecording (HAMR) have been developed to improve writing technology. InMAMR, elements added to the head 540 generate an additional field thatsupplements the magnetic field ordinarily produced by the writetransducer, thereby providing a stronger effective write field. In HAMR,elements added to the head 540 heat a localized area on the surface ofthe recording media (e.g., the disk 520) to reduce its coercivity,thereby enabling the magnetic field generated by the write transducer,which otherwise would be of insufficient strength, to set themagnetization of the localized area. Although these more advancedtechniques can provide improved storage density, there is a limit to howsmall the storage locations can be, and the head 540 needs to fly closeto the surface of the disk 520 to provide sufficiently strong magneticfields.

The inventors had the insight that adding an assistive mechanism to thestorage media instead of, or in addition to, the head 540 would offerseveral advantages relative to prior-art recording techniques. First, ifused in a media with a single recording layer, an assistive mechanismcould allow the head 540 to fly further from the surface of the mediabecause an assist would be provided from within the media, in closerproximity to the storage location being written to or read from. Second,if used in a media with two or more recording layers, an assistivemechanism could enable the media to record more data, thereby increasingits overall storage capacity. Third, an assistive mechanism within themedia could be used to enable remote reading of the data on a storagemedia, thereby eliminating the need for a head 540 to fly over the mediato read data. Such a system may be particularly attractive for archiveddata.

These and other advantages are enabled in the systems and methodsdisclosed herein. Some embodiments of data storage systems includeembedded disconnected circuits (EDC) within a data storage media toimprove the performance of the data storage system (e.g., one or more ofits data storage capacity, its durability, its data access speed, etc.)or to relax the requirements on elements of the data storage system(e.g., the distance between the write transducer and the media duringwrite and/or read operations, the slider's fly height, the density ofstorage locations one or more recording layers of the media, etc.). Asdiscussed herein, the EDC may be used in a number of ways to assistrecording data to the media and/or reading data from the media.

In some embodiments, the EDC assist a write transducer to write data toa recording layer of a media. The write transducer may be a conventionalwrite transducer (e.g., it may or may not include components in additionto the write pole, coil, and return pole, such as those used in HAMR,MAMR, etc.). The recording layer assisted by the EDC may be the onlyrecording layer on the media, or it may be an additional (e.g., second,third, etc.) recording layer added to the media. In some embodiments,the media includes at two recording layers, and the EDC enable the useof at least one of the two recording layers.

In some embodiments, the EDC assist in reading data from a recordinglayer. In some embodiments, the EDC include a read sensor that ispositioned near (e.g., over, under, adjacent to, etc.) one or morestorage locations to read the contents of the one or more storagelocations and to send a wireless signal providing the contents of thestorage location(s) to a signal processing component of the data storagedevice. For example, the read sensor may comprise a resistive element,the resistance of which changes in response to the magnetization of thestorage location(s). In some embodiments, the EDC are capable of readingone or more nearby storage locations and transmitting a wireless signalproviding information (e.g., about the contents, identity, and/orlocation of the storage location(s); about the identity and/or locationof the EDC; etc.) to a receiver embedded in a slider that flies over themedia. In some embodiments, reading is coordinated by reader circuitrythat is located remotely from the media (i.e., the reader circuitry isnot included in a slider that flies over the media), and the EDC arecapable of receiving wireless read commands and transmitting wirelessread responses.

Media with EDC

FIG. 2A illustrates a cross-sectional view of an exemplary layered mediastack 200A that may be included in a conventional hard disk 520 usingperpendicular magnetic recording (PMR) with a single depth of bitsstored in a single recording layer 260 located near the surface of themedia. The media includes a bottom substrate 205 (e.g., an aluminumplatter), an adhesion layer 210 (e.g., NiP plating, an AlTi layer,etc.), a soft underlayer (SUL) 215 (e.g., a soft alloy containingcobalt, nickel, iron, tantalum, and/or zirconium), a ruthenium (Ru)interlayer 220, a recording layer 260, a carbon overcoat layer 235(e.g., a carbon bilayer, the bottom layer being CHx and the top layerbeing CNx), and a lubricant layer 240.

The recording layer 260 may include, for example, thin films with aplurality of magnetic grains, each grain having a magnetic easy axissubstantially perpendicular to the media surface, thereby allowing thegrains to be vertically magnetized. The magnetic grains may comprise amagnetic material such as, for example, CoPt, CoPtCr, CoPtCrB, etc. Tomaintain a highly segregated magnetic layer, one or more segregants maybe added to the magnetic material.

The recording layer 260 may be configured in any suitable arrangement.FIGS. 2B and 2C illustrate two possible arrangements of the recordinglayer 260. FIG. 2B shows a recording layer 260 with two sublayers: anoxide sublayer 228, which includes an oxide, and a capping sublayer 230,which does not include an oxide. The oxide sublayer 228 may comprise,for example, a CoPtCr alloy with one or more segregants includingvarious oxides such as SiOx, TaOx, TiOx, and/or CrOx, and/or variouselements such as B and Ti.

FIG. 2C shows a recording layer 260 with an exchange coupling sublayer232 inserted between the oxide sublayer 228 and the capping sublayer230. The exchange coupling sublayer 232 may be formed of materials suchas, for example, Co alloys including Ru, Cr, Pt and/or B. The exchangecoupling sublayer 232 provides for a reduction of interfacial exchangecoupling strength between the oxide sublayer 228 and the cappingsublayer 230. In addition to or instead of the exchange couplingsublayer 232, various other layers can be introduced between the oxidesublayer 228 and the capping sublayer 230 to improve the performance ofthe recording layer 260.

The media stack 200A illustrated in FIG. 2A and the recording layers 260illustrated in FIGS. 2B and 2C are merely examples of the layers thatmay be included in a media stack. Variants may include media withdifferent numbers of layers and different materials than shown in FIGS.2A-2C. For example, U.S. Pat. No. 7,998,607 to Ikeda, which is herebyincorporated by reference in its entirety for all purposes, discloses apartially-oxidized capping layer that may be used in accordance withsome embodiments. U.S. Pat. No. 8,202,636 to Choe et al., which is alsohereby incorporated by reference in its entirety for all purposes,discloses media for perpendicular magnetic recording that controlanisotropy levels in different sublayers of the magnetic recordinglayer(s) 260 of the media.

FIGS. 2D-2F illustrate how the exemplary media stack 200A of FIG. 2A maybe modified to include the EDC disclosed herein. Again, the materialsand layers illustrated are merely examples, and a media stack mayinclude additional or fewer layers having different characteristics. Itis to be understood that the principles disclosed herein are applicableto other media having different numbers or orders of layers, or usingdifferent materials.

FIG. 2D illustrates a cross-sectional view of an exemplary media stack200B in accordance with some embodiments. The media stack 200B includesmany of the layers discussed above in the context of FIG. 2A. Instead ofthe conventional recording layer 260, the media stack 200B includes anEDC-assisted recording layer 225, which is assisted by an EDC layer 250added to the media stack 200B. The EDC-assisted recording layer 225 maybe indistinguishable from a conventional recording layer 260 but isreferred to as the EDC-assisted recording layer 225 because the EDClayer 250 assists in the reading from and/or writing to the EDC-assistedrecording layer 225. In general, the discussion above of theconventional recording layer 260 (e.g., regarding materials, layers,properties, etc.) applies with equal force to the EDC-assisted recordinglayer 225. One key difference between a conventional recording layer 260and an EDC-assisted recording layer 225, as those terms are used herein,is that reading from and/or writing to the EDC-assisted recording layer225 is potentially assisted by EDC, whereas reading from and/or writingto the conventional recording layer 260 is accomplished without theassistance of EDC.

In the media stack 200B, the EDC layer 250 is embedded between the SUL215 and the Ru interlayer 220. FIG. 2E illustrates an exemplary EDClayer 250 in accordance with some embodiments. As shown in FIG. 2E, theEDC layer 250 may comprise a set of at least one EDC 150, which may besandwiched by structural support layers 255A, 255B. The structuralcomponents of the EDC 150 are discussed below. In general, thestructural support layers 255A, 255B provide topological support for theEDC 150 and for other layers that may be used in magnetic recording(e.g., the exemplary layers 210, 215, 220, etc.). If present, thestructural support layers 255A, 255B above and below the EDC layer 250may be different, depending on the requirements for fabricating thelayers adjacent to the structural support layers 255A, 255B. Armed withthe disclosures herein, skilled artisans will understand how to selectthe characteristics (e.g., material, thickness, etc.) of and fabricatethe structural support layers 255A, 255B.

FIG. 2F illustrates a cross-sectional view of another exemplary layeredmedia stack 200C in accordance with some embodiments. In the media stack200C, an EDC layer 250 is embedded in the media between two adhesionlayers 210A, 210B, which reside between the SUL 215 and the substrate205, and the EDC-assisted recording layer 225 resides between the carbonovercoat layer 235 and the Ru interlayer 220. As in FIG. 2D, the EDClayer 250 may comprise the EDC 150 sandwiched by structural supportlayers 255A, 255B. In other words, the EDC 150, which may be sandwichedby structural support layers 255A, 255B, are sandwiched between the twoadhesion layers 210A, 210B in the embodiment of FIG. 2F.

FIG. 2G illustrates a cross-sectional view of another exemplary layeredmedia stack 200D in accordance with some embodiments. In the media stack200D, an EDC layer 250 is embedded in the media between the adhesionlayer 210 and the Ru interlayer 220, and the EDC-assisted recordinglayer 225 is disposed between the Ru interlayer 220 and the carbonovercoat layer 235. As in FIGS. 2D and 2F, the EDC layer 250 maycomprise the EDC 150 sandwiched between structural support layers 255A,255B as shown in FIG. 2E. In the example of FIG. 2G, the EDC layer 250replaces the SUL 215 and, as a result, may also be imbued with some orall of the characteristics of the SUL 215.

In some embodiments, the EDC 150 are added to assist writing to and/orreading from a media that includes only one EDC-assisted recording layer225 instead of a conventional recording layer. In some embodiments, theEDC 150 are added to convert the media from a two-dimensional storagemedia having only a single recording layer (whether conventional orEDC-assisted) to a three-dimensional storage media by providing theability to store data in EDC-assisted recording layers 225 that areunder the single recording layer (i.e., whether a conventional recordinglayer 260 or an EDC-assisted recording layer 225).

FIGS. 3A-3C and 5A-5B are simplified illustrations of magnetic storagesystems in accordance with some embodiments. For ease of description,FIGS. 3A-3C and 5A-5B show only the head 540, the recording layer(s)260, 225, the EDC layer(s) 250, and, if present, an optional isolationlayer 170 of the media stack. As explained above, the media stackgenerally includes additional layers that are not illustrated in FIGS.3A-3C and 5A-5B.

FIG. 3A illustrates an exemplary magnetic storage system 100A with amedia stack that includes an EDC-assisted recording layer 225 and an EDClayer 250 in accordance with some embodiments. As explained below, theEDC 150 in the EDC layer 250 may assist the head 540 to write data toand/or read data from the recording layer 225. In the exampleillustrated in FIG. 3A, the EDC-assisted recording layer 225 replaces aconventional recording layer 260 and may result in a media stack thatlooks similar or identical to the media stack 200B, 200C, or 200D ofFIGS. 2D, 2F, and 2G, respectively.

FIG. 3B illustrates the use of EDC 150 in an example magnetic recordingsystem 100B to enable the use of an EDC-assisted recording layer 225 inaddition to a conventional recording layer 260 in accordance with someembodiments. In the example shown in FIG. 3B, an EDC layer 250 residesbetween the conventional recording layer 260 and the EDC-assistedrecording layer 225. The conventional recording layer 260 is used in theconventional way, i.e., it is written to and read from by the head 540without assistance from the EDC 150 in the EDC layer 250. An optionalisolation layer 170, which may provide structural, electromagnetic,and/or thermal isolation, may be disposed between the conventionalrecording layer 260 and the EDC layer 250 to mitigate interactionsbetween the EDC 150 and the conventional recording layer 260, or toprevent the EDC 150 from interacting with or affecting the conventionalrecording layer 260. Armed with the disclosures herein, skilled artisanswill understand how to select suitable materials for and characteristicsof the isolation layer 170.

FIGS. 4A and 4B illustrate certain elements of the magnetic recordingsystem 100B in more detail. FIG. 4A shows a write transducer 110 and aportion of the media 120. As shown in FIG. 4A, a magnetic storage media120 comprises a conventional recording layer 260 near the surface of themedia 120 that faces the write transducer 110, and an EDC-assistedrecording layer 225 located deeper in the media 120, further away fromthe write transducer 110. An EDC layer 250 is disposed above andadjacent to the EDC-assisted recording layer 225. It is to be understoodthat the EDC layer 250 need not be adjacent to the EDC-assistedrecording layer 225, but close proximity may be desirable to maximizethe impact of the EDC 150 on the EDC-assisted recording layer 225. Inthe example illustrated in FIG. 4A, the isolation layer 170 is shownbetween the EDC layer 250 and the conventional recording layer 260. Asdiscussed above, the isolation layer 170 may mitigate or preventinteraction between the EDC 150 and the conventional recording layer260.

FIG. 4B is a closer view of a portion of the magnetic storage media 120of FIG. 4A. As shown, the conventional recording layer 260 includes aplurality of storage locations 135A, 135B, 135C, etc. The EDC-assistedrecording layer 225 includes a plurality of EDC-assisted storagelocations 145A, 145B, 145C, etc., and the EDC layer 250 includes aplurality of EDC 150A, 150B, 150C, etc. (To avoid obscuring the drawing,FIG. 4B does not illustrate any structural support layers 255 that mightbe present in the EDC layer 250.) A storage location 135, 145 can be anydefined portion of the media that stores data. For example, the storagelocations 135 and/or 145 may be within a track or sector. As anotherexample, the storage locations 135 and/or 145 may be in the form ofbit-patterned media. Bit patterned media are described in U.S. Pat. No.7,324,294 to Moser and U.S. Pat. No. 6,947,235 to Albrecht et al., bothof which are hereby incorporated by reference in their entireties.

The EDC-assisted storage locations 145 in the EDC-assisted recordinglayer 225 may be written to and/or read from by selectively activatingone or more associated EDC 150 in the EDC layer 250 to write to and/orread from selected ones of the EDC-assisted storage locations 145. Asillustrated in FIGS. 4A and 4B, the number and dimensions of the storagelocations 135 need not be the same as the number and dimensions of theEDC-assisted storage locations 145. For example, it may be desirable touse different or optimized sizes and/or shapes (e.g., geometrics,dimensions, configurations, etc.) for the storage locations 145 in theEDC-assisted recording layer 225 than in the conventional recordinglayer 260 to maximize the effectiveness of the EDC 150. Furthermore,although FIG. 4B illustrates the EDC-assisted storage locations 145 andthe EDC 150 in a one-to-one ratio, a single EDC 150 may be used duringread and/or write operations involving multiple EDC-assisted storagelocations 145. For example, the EDC 150 may enable bank reading or bankwriting whereby multiple EDC-assisted storage locations 145 are readfrom or written to simultaneously. Similarly, multiple EDC 150 may beused during read and/or write operations involving a single EDC-assistedstorage location 145. For example, a first EDC 150 may assist in thewriting process, and a second EDC 150 may assist in the reading process.

FIG. 3C illustrates another exemplary magnetic recording system 100Cthat enables the use of an EDC-assisted recording layer 225 in additionto a conventional recording layer 260 in accordance with someembodiments. In the example system 100C, the EDC layer 250 resides belowthe EDC-assisted recording layer 225. This positioning of the EDC layer250 may reduce or eliminate any need for an optional isolation layer 170between the first and second recording layers 225A, 225B. Although notillustrated in FIG. 3C, the example system 100C may also include anisolation layer 170, which may be disposed, for example, between thefirst and second recording layers 225A, 225B.

FIGS. 4C and 4D illustrate certain elements of the magnetic recordingsystem 100C shown in FIG. 3C in more detail. As shown in FIG. 4C, amagnetic storage media 120 comprises a conventional recording layer 260near the surface of the media 120, and an EDC-assisted recording layer225 located deeper in the media 120. An EDC layer 250 is disposed belowand adjacent to the EDC-assisted recording layer 225. It is to beunderstood that the EDC layer 250 need not be adjacent to theEDC-assisted recording layer 225, but close proximity may be desirableto maximize the ability of the EDC 150 to assist the EDC-assistedrecording layer 225. Unlike in FIG. 3C, in the example illustrated inFIG. 4C, an optional isolation layer 170 is provided between theEDC-assisted recording layer 225 and the conventional recording layer260.

FIG. 4D is a closer view of a portion of the magnetic storage media 120of FIG. 4C. As shown, the conventional recording layer 260 includes aplurality of storage locations 135A, 135B, 135C, etc. The EDC-assistedrecording layer 225 includes a plurality of EDC-assisted storagelocations 145A, 145B, 145C, etc., and the EDC layer 250 includes aplurality of EDC 150A, 150B, 150C, etc. (and may also include structuralsupport layers 255 as discussed above). As illustrated in FIGS. 4C and4D, and as discussed above in the context of FIGS. 4A and 4B, the numberand dimensions of the EDC-assisted storage locations 145 need not be thesame as the number and dimensions of the conventional storage locations135. Furthermore, a single EDC 150 may be used during read and/or writeoperations involving multiple EDC-assisted storage locations 145.Similarly, multiple EDC 150 may be used during read and/or writeoperations involving a single EDC-assisted storage location 145. Forexample, a first EDC 150 may assist in the writing process, and a secondEDC 150 may assist in the reading process.

FIG. 5A illustrates another exemplary magnetic recording system 100Dthat enables the use of multiple EDC-assisted recording layers 225 inaccordance with some embodiments. The example system 100D includes twoEDC layers 250. The first EDC layer 250A assists the head 540 to writeto the first EDC-assisted recording layer 225A, and the second EDC layer250B assists the head 540 to write to the second EDC-assisted recordinglayer 225B. Thus, the recording process for each of the first and secondEDC-assisted recording layers 225A, 225B takes advantage of EDC 150.Similarly, the reading process may also take advantage of the EDC 150 inthe EDC layers 250A, 250B. An optional isolation layer 170 (e.g., asdescribed above in the context of FIG. 3B) may be disposed between thefirst EDC layer 250A and the second EDC-assisted recording layer 225B tomitigate or prevent interactions between the EDC 150 in the first EDClayer 250A and the storage locations 145 in the second EDC-assistedrecording layer 225B.

FIGS. 6A and 6B illustrate certain elements of the magnetic recordingsystem 100D in more detail. As shown in FIG. 6A, a magnetic storagemedia 120 comprises a first EDC-assisted recording layer 225A near thesurface of the media 120, and a second EDC-assisted recording layer 225Blocated deeper in the media 120. A first EDC layer 250A is disposedbelow and adjacent to the first EDC-assisted recording layer 225A, and asecond EDC layer 250B is disposed below and adjacent to the secondEDC-assisted recording layer 225B. It is to be understood that the firstand second EDC layers 250A, 250B need not be adjacent to theirrespective EDC-assisted recording layers 225, but close proximity may bedesirable to maximize the impact of the EDC 150 on the EDC-assistedrecording layers 225. In the example illustrated in FIG. 6A, anisolation layer 170 is provided between the second EDC-assistedrecording layer 225B and the first EDC layer 250A.

FIG. 6B is a closer view of a portion of the magnetic storage media 120of FIG. 6A. As shown, the first EDC-assisted recording layer 225Aincludes a plurality of EDC-assisted storage locations 145P, 145Q, 145R,etc., and the second EDC-assisted recording layer 225B includes aplurality of EDC-assisted storage locations 145A, 145B, 145C, etc. Thefirst EDC layer 250A includes a plurality of EDC 150F, 150G, 150H, etc.,and the second EDC layer 250B includes a plurality of EDC 150A, 150B,150C, etc. One or both of the first and second EDC layers 250A, 250B mayalso include structural support layers 255 as discussed above. Asillustrated in FIGS. 6A and 6B, the number and dimensions of theEDC-assisted storage locations 145 in the first EDC-assisted recordinglayer 225A need not be the same as the number and dimensions of theEDC-assisted storage locations 145 in the second EDC-assisted recordinglayer 225B. Furthermore, a single EDC 150 in the first EDC layer 250Amaybe used during read and/or write operations involving multipleEDC-assisted storage locations 145 in the first EDC-assisted recordinglayer 225A, and a single EDC 150 in the second EDC layer 250B may beused during read and/or write operations involving multiple EDC-assistedstorage locations 145 in the second EDC-assisted recording layer 225B.Similarly, multiple EDC 150 in either EDC layer 250A, 250B may be usedduring read and/or write operations involving a single EDC-assistedstorage location 145. For example, a first EDC 150 may assist in thewriting process, and a second EDC 150 may assist in the reading process.

FIG. 5B illustrates another exemplary magnetic recording system 100Ethat enables the use of multiple EDC-assisted recording layers 225 inaccordance with some embodiments. Like the exemplary system 100D of FIG.5A, the example system 100E includes two EDC layers 250. The first EDClayer 250A assists the head 540 to write to the first EDC-assistedrecording layer 225A, and the second EDC layer 250B assists the head 540to write to the second EDC-assisted recording layer 225B. Thus therecording process for each of the first and second EDC-assistedrecording layers 225A, 225B takes advantage of EDC 150. In the system100E, the first and second EDC-assisted recording layers 225A, 225B areseparated by the first and second EDC layers 250A, 250B. An optionalisolation layer 170 (e.g., as described above in the context of FIG. 3B)may be disposed between the first and second EDC layers 250A and 250B tomitigate or prevent interactions between the EDC 150 in the first EDClayer 250A and the second EDC-assisted recording layer 225B, and tomitigate or prevent interactions between the EDC 150 in the second EDClayer 250B and the first EDC-assisted recording layer 225A.

FIGS. 6C and 6D illustrate certain elements of the magnetic recordingsystem 100E in more detail. As shown in FIG. 6C, a magnetic storagemedia 120 comprises a first EDC-assisted recording layer 225A near thesurface of the media 120, and a second EDC-assisted recording layer 225Blocated deeper in the media 120. A first EDC layer 250A is disposedbelow and adjacent to the first EDC-assisted recording layer 225A, and asecond EDC layer 250B is disposed above and adjacent to the secondEDC-assisted recording layer 225B. It is to be understood that the firstand second EDC layers 250A, 250B need not be adjacent to theirrespective EDC-assisted recording layers 225, but close proximity may bedesirable to maximize the impact of the EDC 150 in an EDC layer 250 onthe target EDC-assisted recording layer 225. In the example illustratedin FIG. 6C, an isolation layer 170 is provided between the first andsecond EDC layers 250A and 250B.

FIG. 6D is a closer view of a portion of the magnetic storage media 120of FIG. 6C. As shown, the first EDC-assisted recording layer 225Aincludes a plurality of EDC-assisted storage locations 145P, 145Q, 145R,etc., and the second EDC-assisted recording layer 225B includes aplurality of EDC-assisted storage locations 145A, 145B, 145C, etc. Thefirst EDC layer 250A includes a plurality of EDC 150F, 150G, 150H, etc.,and the second EDC layer 250B includes a plurality of EDC 150A, 150B,150C, etc. One or both of the first and second EDC layers 250A, 250B mayalso include structural support layers 255 as discussed above. Asillustrated in FIGS. 6C and 6D, and as discussed above in the context ofFIGS. 4A and 4B, the number and dimensions of the EDC-assisted storagelocations 145P, 145Q, 145R, etc. in the first EDC-assisted recordinglayer 225A need not be the same as the number and dimensions of theEDC-assisted storage locations 145A, 145B, 145C, etc. in the secondEDC-assisted recording layer 225B. Furthermore, a single EDC 150 in thefirst EDC layer 250A maybe used during read and/or write operationsinvolving multiple storage locations 145 in the first EDC-assistedrecording layer 225A, and a single EDC 150 in the second EDC layer 250Bmay be used during read and/or write operations involving multipleEDC-assisted storage locations 145 in the second EDC-assisted recordinglayer 225B.

It is to be understood that in general, a recording media can includeany number of recording layers 260, 225, conventional and/orEDC-assisted, and EDC layers 250. The presence of EDC-assisted recordinglayers 225 in addition to conventional recording layers 260 may providean opportunity to relax some of the requirements on the conventionalrecording layer(s) 260 and/or the head 540. For example, if a mediaincludes both a conventional recording layer 260 and an EDC-assistedrecording layer 225, the total number of storage locations, some ofwhich are EDC-assisted and others of which are not, may exceed the totalnumber available in a conventional media. Therefore, it is possible torelax some of the requirements on the conventional recording layer 260and/or other characteristics of the data storage device 100 (e.g.,slider fly height, density of storage locations, etc.) withoutsacrificing the overall data storage capacity of the data storage device100. Moreover, the total number of storage locations 135, 145 in a mediathat includes one or more EDC layers 250 may substantially exceed thenumber that would be available in a media with only a conventionalrecording layer 260, even if the storage density within a conventionalrecording layer 260 is reduced.

Moreover, the number of EDC layers 250 included in a recording medianeed not be the same as the number of additional recording layers. Asingle EDC layer 150 may be capable of assisting reading and/or writingof multiple EDC-assisted recording layers 225. For example, an EDC layer250 may be sandwiched between two EDC-assisted recording layers 225 andcapable of assisting to read from and/or write to both EDC-assistedrecording layers 225. The EDC 150 in such an EDC layer 250 may becapable of selectively reading from/writing to each of the EDC-assistedrecording layers 225.

Furthermore, as explained above, EDC 150 may be added to a media thatincludes only a single recording layer to assist in writing to and/orreading from that recording layer, thereby converting a conventionalrecording layer 260 to an EDC-assisted recording layer 225.

The EDC

The exemplary media illustrated in FIGS. 2D, 2F, 2G, and 3A-6D can storedata in the EDC-assisted recording layers 225 by setting themagnetizations of the EDC-assisted storage locations 145. As describedbelow, the EDC 150 embedded in the EDC layer(s) 250 of the media provideassistance during the writing process, the reading process, or both.

FIG. 7A illustrates an EDC 150 in accordance with some embodiments. TheEDC 150 includes an antenna 152 and circuitry 155. The EDC 150 may be afrequency-selective circuit. For example, the antenna 152 may comprise afrequency-selective antenna in which the oscillating electric andmagnetic fields of an incoming radio wave create oscillating currents inthe antenna 152 only if the incoming radio wave is of a particularfrequency or within a particular frequency range. Alternatively or inaddition, the antenna 152 may include a frequency-selective surface(FSS) (e.g., an optical filter, a metal-mesh optical filter, or anysurface having a pattern designed to reflect, transmit, or absorbelectromagnetic fields based on the frequency of the field). The antenna152 may be omnidirectional (i.e., capable of receiving energyapproximately equally from all directions) or directional (i.e., moresensitive to energy received from a particular direction). Ifdirectional, the antenna 152 may be configured (e.g., in design, inplacement, in orientation, etc.) to maximize its coupling toelectromagnetic energy in a particular direction. The antenna 152 may beof any suitable type (e.g., a monopole antenna, a dipole antenna, etc.).Furthermore, the antenna 152 may be an array of antennas (e.g., a phasedarray, a log-periodic dipole array, etc.).

Different EDC 150 may have antennas 152 with differing characteristics.For example, in some embodiments, frequency diversity enables theselective activation of the EDC 150. In such embodiments, the antenna152 of a first EDC 150 may be configured to create oscillating currentsonly when a signal having a first frequency is received, and the antenna152 of a second EDC 150 may be configured to create oscillating currentsonly when a signal having a second frequency is received so that thefirst EDC 150 may be activated independently of the second EDC 150, andvice versa.

The circuitry 155 of the EDC 150 may include circuitry for reading fromthe media and/or circuitry for writing to the media. In general, thecircuitry 155 of the EDC 150 may comprise any circuit element (e.g.,active, passive, analog, digital, etc.). Examples of circuit elementsthat may be included in the circuitry 155 include resistors, capacitors,inductors, transistors, operational amplifiers, diodes, gates,transformers, switches, etc. In operation, the EDC 150 is energized by atime-varying electromagnetic radio-frequency (RF) signal transmitted bya circuit of the data storage device (e.g., a circuit that is separatefrom the EDC 150 and its circuitry 155). The RF signal generates an ACvoltage across the antenna 152, which supplies power to the circuitry155. The AC voltage may optionally be rectified. As described below, theenergized EDC 150 can then (a) assist the head 540 to write to arecording layer 225 and/or (b) read or assist in reading datapreviously-stored in a recording layer 225.

The EDC 150 may be distributed or embedded within the EDC layer 250 inany suitable pattern and at any suitable density. As just one example,one EDC 150 may be included in the media for every 200 bits in a Tb/in²surface, assuming the area of the antenna 152 is 1 μm².

FIG. 7B illustrates an exemplary EDC 150 in which the circuitry 155comprises a resistive element 156 in accordance with some embodiments.In operation, the power supplied by the antenna 152 to the resistiveelement 156 causes the resistive element 156 to generate heat. As aresult, because the EDC layer 250 is adjacent to or near the recordinglayer 225, the portion of the recording layer 225 near the resistiveelement 156 is heated, which lowers its coercivity and allows the writetransducer 110 of the head 540 to record data to the heated storagelocation(s) in that localized region of the media.

FIG. 7C illustrates an exemplary EDC 150 in which the circuitry 155comprises a resonator 157 in accordance with some embodiments. Inoperation, the power supplied by the antenna 152 to the resonator 157causes the resonator 157 to emit electromagnetic waves that addconstructively to the write field generated by the write transducer 110,thereby providing a sufficient field to switch nearby storage locationsin the recording layer 225.

FIG. 7D illustrates an exemplary EDC 150 in which the circuitry 155comprises a heat generator 158. Similarly to the resistive element 156described above, the heat generator 158 causes the portion of therecording layer 225 near it to heat, which lowers its coercivity andallows the write transducer 110 to more easily record data to the heatedstorage location(s) near the heat generator 158.

FIG. 7E illustrates an exemplary EDC 150 in which the circuitry 155comprises an active circuit 160. In operation, the power supplied by theantenna 152 to the active circuit 160 causes the active circuit 160 toprovide an assist to the write transducer 110. For example, the activecircuit 160 may generate a microwave field that augments the writefield. As another example, the active circuit 160 may generateelectromagnetic energy that heats the recording layer near the activecircuit 160 to lower its coercivity and allow the magnetization of oneor more storage locations to be adjusted more easily.

FIG. 7F illustrates an exemplary EDC 150 in which the circuitry 155comprises a spin-torque oscillator (STO) 162, or a similar spin-torquenanodevice. In operation, the power supplied by the antenna 152 to theSTO 162 causes the magnetization of the STO 162 to oscillate andgenerate a microwave field that augments the field of the writetransducer 110, thereby enabling writing to the storage location(s)assisted by that EDC 150.

FIG. 7G illustrates an exemplary EDC 150 in which the circuitry 155comprises a read sensor 164. The read sensor 164 may be configured tovary in response to a magnetization of one or more storage location(s)assisted by the EDC 150. In some embodiments, the read sensor 164 is aconventional magnetoresistive (MR) sensor (i.e., a “spin-valve” sensorbased on the giant magnetoresistance (GMR) effect). A GMR spin-valvesensor has a stack of layers that includes two ferromagnetic layersseparated by a nonmagnetic electrically conductive spacer layer, whichis typically copper (Cu). One ferromagnetic layer adjacent the spacerlayer has its magnetization direction fixed, such as by being pinned byexchange coupling with an adjacent antiferromagnetic layer, and isreferred to as the reference layer. The other ferromagnetic layeradjacent the spacer layer has its magnetization direction free to rotatein the presence of an external magnetic field and is referred to as thesensing or free layer. With a sense current applied to the sensor, therotation of the free-layer magnetization relative to the reference-layermagnetization due to the presence of an external magnetic field isdetectable as a change in electrical resistance.

In some embodiments, the read sensor 164 is a magnetic tunnel junctionsensor, also called a tunneling MR or TMR sensor, in which thenonmagnetic spacer layer is a very thin nonmagnetic insulating tunnelbarrier layer such as TiO₂, MgO or Al₂O₃. The barrier layer issufficiently thin that quantum-mechanical tunneling of charge carriersoccurs between the two ferromagnetic layers. This quantum-mechanicaltunneling process is electron spin dependent, which means that anelectrical resistance measured when applying a sense current across thejunction depends on the spin-dependent electronic properties of theferromagnetic and barrier layers, and is a function of the relativeorientation of the magnetizations of the two ferromagnetic layers.

As will be appreciated by skilled artisans, there are myriad possibleelements and combinations of elements that may be included in thecircuitry 155, and the examples provided herein are not intended to belimiting. Moreover, an EDC 150 may include more than one of the elementsdescribed in the context of FIGS. 7A-7G. For example, an EDC 150 maycomprise an element (e.g., 156, 157, 158, 160, 162, etc.) to assist inwriting to the EDC-assisted recording layer 225 and a separate element(e.g., 164, etc.) to assist in reading from the EDC-assisted recordinglayer 225.

Using EDC to Write to a Deeper Recording Layer Using a Conventional Head

For ease of terminology, many of the exemplary embodiments discussedbelow are typically discussed as if the media includes only oneEDC-assisted recording layer 225, but it is to be appreciated that, asexplained previously, the techniques disclosed herein can be usedadvantageously to provide additional EDC-assisted recording layers 225.For example, if the surface of the platter is in the x-y plane, thedisclosures herein may be used to provide for multiple EDC-assistedrecording layers 225 in the z-direction.

In some embodiments, because the EDC-assisted recording layer 225 liesunderneath the conventional recording layer 260, the objective is towrite data to the EDC-assisted recording layer 225 while preservinginformation recorded in other layers (e.g., in the conventionalrecording layer 260 and in any additional EDC-assisted recording layers225 previously written to). In other words, the goal is to write to theconventional recording layer 260 and the EDC-assisted recording layer(s)225 independently.

In some embodiments, the exchange break layers of the media are tuned sothat, absent the assistance of the EDC 150, the EDC-assisted recordinglayer 225 is more difficult to write than the conventional recordinglayer 260. In such embodiments, when the EDC 150 are not energized, themagnetic field generated by the write transducer 110 is insufficient toovercome the coercivity of the EDC-assisted storage locations 145 in theEDC-assisted recording layer 225, and none of the cells in theEDC-assisted recording layer 225 are written to. When an EDC 150 isenergized, it generates a field that augments the writer's magneticfield (or otherwise provides an assist, such as, e.g., by heating theEDC-assisted recording layer 225) and allows one or more storagelocations 145 in the EDC-assisted recording layer 225 to be written to.

In embodiments in which the media includes one conventional recordinglayer 260 and an EDC-assisted recording layer 225, the coercivities ofthe layers can be different to provide more control over recording inthe EDC-assisted recording layer 225. For example, referring again toFIG. 3C, the EDC-assisted recording layer 225 can have a highercoercivity than the conventional recording layer 260 so that when theEDC 150 in the EDC layer 250 are inactive, the magnetic field generatedby the write transducer 110 is strong enough to switch the magnetizationin the conventional recording layer 260, but it is insufficient toswitch the magnetization of the EDC-assisted recording layer 225. Incontrast, when the EDC 150 in the EDC layer 250 are energized, themagnetic field generated by the write transducer 110, with theassistance provided by the EDC 150 (e.g., in the form of heat or a fieldthat adds constructively to or otherwise augments the field generated bythe write transducer 110, as described above) is sufficient to switchthe magnetization of the EDC-assisted recording layer 225.

In some embodiments, the conventional recording layer 260 can be writtento without affecting the EDC-assisted recording layer 225, but writingto the EDC-assisted recording layer 225 affects the conventionalrecording layer 260. For example, the coercivity of the conventionalrecording layer 260 may be lower than the coercivity of the EDC-assistedrecording layer 225. In some such embodiments, the write processcomprises two steps: a first step in which at least one EDC 150 in theEDC layer 250 is activated, and both the conventional recording layer260 and the EDC-assisted recording layer 225 are written to, and asecond step in which all EDC 150 are inactive and only the conventionalrecording layer 260 is written to.

In some embodiments in which a two-step recording procedure is used, theEDC 150 are used in conjunction with a recording process in the firststep to enable the EDC-assisted recording layer 225 to be written.Because the coercivity of the conventional recording layer 260 is lowerthan that of the EDC-assisted recording layer 225, the EDC-assistedrecording process may also cause one or more storage locations 135 inthe conventional recording layer 260 to be written to. For example, thefield emitted by the write transducer 110 may change the magnetizationof an EDC-assisted storage location 145 in the EDC-assisted recordinglayer 225, which is desired, and it may also change the magnetization ofone or more conventional storage locations 135 in the conventionalrecording layer 260, which is not desired. In general, the storagelocations 135 in the conventional recording layer 260 that are mostlikely to be overwritten when the EDC-assisted storage locations 145 arewritten to are those closest to the EDC-assisted storage locations 145,because those storage locations 135 are most likely to be affected bythe write transducer 110's magnetic field. In the second step, the EDC150 are not activated, and the magnetic field strength may be reduced toa level that is insufficient to overcome the coercivity of theEDC-assisted recording layer 225. The storage locations 135 in theconventional recording layer 260 may then be written to withoutaffecting the data previously stored in the EDC-assisted recording layer225 in the first step.

A similar approach allows the preservation of data previously stored inthe conventional recording layer 260 when the EDC-assisted recordinglayer 225 is written. In some embodiments, prior to beginning theprocess to write to the EDC-assisted recording layer 225, the contentsof the storage location(s) 135 of the conventional recording layer 260that may be affected by the process of writing to the EDC-assistedrecording layer 225 (e.g., the storage locations 135 that are closest tothe EDC-assisted storage locations 145 to be written to) are noted. Thenthe EDC(s) 150 are activated, and selected EDC-assisted storagelocations 145 in the EDC-assisted recording layer 225 are written to. Asexplained above, this process may modify the contents of certain storagelocations(s) 135 of the conventional recording layer 260 (e.g., thosethat are closest to the EDC-assisted storage locations 145 being writtento). The EDC(s) 150 are then deactivated, and the affected storagelocation(s) 135 of the conventional recording layer 260 are re-writtento restore the contents of the storage location(s) 135.

It is also possible to write to the EDC-assisted recording layer 225without affecting the contents of storage locations 135 in theconventional recording layer 260. For example, resonators may be used toenable independent selection of the EDC-assisted recording layer 225 forwriting without affecting the conventional recording layer 260.

In order for the EDC 150 to assist in writing to an EDC-assistedrecording layer 225, the EDC 150 must be activated. FIG. 8A is aconceptual illustration of a magnetic storage system 100 in accordancewith some embodiments. As shown in FIG. 8A, the media has beenpartitioned into sectors. Sectors 1 and 2 are shown. Each sectorincludes a plurality of EDC 150 and EDC-assisted storage locations 145.FIG. 8A illustrates one EDC 150 per EDC-assisted storage location 145,but, as explained above, the EDC 150 and EDC-assisted storage locations145 need not be in a one-to-one relationship. For ease of explanation,each sector shown in FIG. 8A is illustrated having only four EDC 150 andfour EDC-assisted storage locations 145. Sector 1 includes EDC 150A,150B, 150C, and 150D and corresponding EDC-assisted storage locations145A, 145B, 145C, and 145D. Sector 2 includes EDC 150E, 150F, 150G, and150H and corresponding EDC-assisted storage locations 145E, 145F, 145G,and 145H. The EDC 150A and 150E are configured to be activated by anactivation signal 180 having a frequency of f1. The EDC 150B and 150Fare configured to be activated by an activation signal 180 having afrequency of f2. The EDC 150C and 150G are configured to be activated byan activation signal 180 having a frequency of f3, and the EDC 150D and150H are configured to be activated by an activation signal 180 having afrequency of f4.

As shown in FIG. 8A, the magnetic storage system 100 comprises a signalgenerator 190 wirelessly coupled to (i.e., configured to transmitwireless signals to and/or receive wireless signals from) the EDC 150.The signal generator 190 includes circuitry to generate wireless signalsand a transmitter capable of transmitting wireless signals. It is to beunderstood that the transmitter of the signal generator 190 may bepositioned in or on the slider 525, or it may be in another locationwithin the data storage device 100 (e.g., in a fixed position not in theimmediate vicinity of the storage location 135, 145 of the media to bewritten to/read from).

In embodiments in which the transmitter of the signal generator 190 ispositioned in or on the slider 525, the signal generator 190 may be inclose proximity to the EDC 150 to be activated and may be able to directan activation signal toward only the EDC 150 to be activated. In suchcases, there may be little risk of unintended activation of other EDC150.

In embodiments in which the signal generator 190 transmits activationsignals from further away (e.g., when the signal generator 190 is in alocation away from the head 540 and/or media), there may be a risk thatthe activation signal activates EDC 150 in addition to the intendedone(s). To mitigate the unintended activation of EDC 150 other than theone(s) intended, the signal generator 190 may comprise a directionalantenna enabling the signal generator 190 to launch the activationsignal 180 in a particular direction (e.g., toward a target EDC 150). Inthe example shown in FIG. 8A, the signal generator 190 is targeting theEDC 150A in Sector 1 and launches the activation signal 180, having thefrequency f1, in the direction of EDC 150A. As illustrated, theactivation signal 180 may also travel in other directions, such astoward Sector 2 (which may be, e.g., an adjacent sector, a sector in anEDC layer 250 other than the one targeted, etc.). Thus, the EDC 150E,which is also configured to respond to activation signals 180 having thefrequency f1, may also be activated by the activation signal 180.

In operation, to activate a specific EDC 150, the signal generator 190generates an activation signal 180 and transmits it to that EDC 150(and, as described above, potentially to other EDC 150), potentiallyusing a directional antenna. The signal generator 190 may be capable ofgenerating activation signals 180 having different characteristics(e.g., frequencies, etc.), as explained further below. To provideselectivity in EDC 150 activation, different EDC antennas 152 may beconfigured to respond to different RF frequencies so that an activationsignal 180 of a selected frequency activates a particular EDC 150 (orset of more than one EDC 150). Moreover, the EDC antennas 152 may bedirectional antennas so that, for example, a selected EDC 150 isactivated by a first activation signal 180 having a frequency of f1received from a first direction but not a second signal having afrequency of f1 received from a second direction (e.g., 90 degreesaway). Thus, one or more characteristics of the RF activation signals180 (e.g., frequency, timing, phase, direction, etc.) that activate thevarious EDC 150 may be used to address or target particular EDC 150 andthe memory cells within range of those EDC 150.

In some embodiments, such as shown in FIG. 8A, the EDC 150 are insectors, and only one EDC 150 in each sector responds to an activationsignal 180 having a particular set of characteristics. In suchembodiments, the activation signal 180 may activate more than one EDC150 (for example, the activation signal 180 shown in FIG. 8A mayactivate both EDC 150A in Sector 1 and EDC 150E in Sector 2), but eachactivated EDC 150 is in a different sector. For write operations using awrite transducer 110 as described above, the write transducer 110 isover only the portion of the media to be written, which corresponds tothe EDC-assisted storage location(s) 145 associated with the activatedEDC 150, and therefore the activation of one or more EDC 150 outside ofthat sector does not cause writing to unintended EDC-assisted storagelocations 145 away from the write transducer 110. As a concrete example,referring to FIG. 8A, the write transducer 110 would be over theEDC-assisted storage location 145A, so even if the activation signal 180were to activate EDC 150E, only the EDC-assisted storage location 145Awould be written to. The EDC-assisted storage location 145E would not beaffected because the write transducer 110 would not generate a fieldstrong enough to switch the magnetization of the EDC-assisted storagelocation 145E.

In the example shown in FIG. 8A, the activation signal 180 has acharacteristic, namely its frequency, selected to activate a particularEDC 150 (or set of EDC 150) in the media. It is to be appreciated thatother aspects of the activation signal 180 may be used instead of or inaddition to the frequency to activate selected EDC 150. Examples ofother characteristics include amplitude, modulation, duty cycle,bandwidth, or any other controllable characteristic of a transmittedsignal.

There are many benefits of using EDC 150 to write to a storage media.For example, higher-capacity storage is feasible because of the abilityto store data in three dimensions of the media instead of only two.Furthermore, the use of EDC 150 eases requirements on the write head andmedia because the EDC 150 provide an assist to the write transducer 110.As a consequence, the write head can be larger, and the same magnitudemagnetic field can be used to write to storage locations 145 in theEDC-assisted recording layer 225 because the EDC 150 supply an assistingfield or other assistive function (e.g., heat to reduce coercivity).Moreover, the media does not need to be as smooth as it needs to bewithout the use of EDC 150 because the head 540 can fly higher above themedia and still provide the same or better performance as in aconventional storage device. Also, the storage device 100 does not needto provide power to the EDC 150 corresponding to storage locations 145that are not being written to. Another advantage is that the EDC 150 canenable bulk or bank writes. The writer may turn on an array of EDC 150in the media and target an RF signal toward that location (or thoselocations), thereby writing to an area of the media.

Reading from a Data Storage Media Using EDC

In some embodiments, EDC 150 embedded in a media are used to read datastored in an EDC-assisted recording layer 225. For example, as explainedabove, the circuitry 155 of an EDC 150 may include read circuitry (e.g.,a read sensor 164) that is activated by an activation signal 180received by the EDC 150 antenna 152. The read circuitry enables an EDC150 to interrogate a nearby EDC-assisted storage location 145 (or anearby set of EDC-assisted storage locations 145). The EDC 150 may alsoinclude transmitting circuitry that enables the EDC 150 to wirelesslytransmit a signal reporting the result of the interrogation to areceiver in the storage system. The receiver may be located on or in aslider 525 that flies over the media, or it may be located away from themedia.

FIGS. 8A and 8B illustrate reading from an EDC-assisted storage location145 in accordance with some embodiments. In operation, the signalgenerator 190 generates and transmits an activation signal 180. Asexplained above, if the transmitter of the signal generator 190 islocated on or in a slider 525 that flies over the media, the activationsignal 180 may be in close proximity to the EDC 150 intended to beactivated. In such embodiments, the activation signal 180 may activateonly the intended EDC 150. In some embodiments, the transmitter of thesignal generator 190 is not in close proximity to the EDC 150 to beactivated, and there is a risk of activating unintended EDC 150. FIG. 8Aillustrates a situation in which both EDC 150A in Sector 1 and EDC 150Ein Sector 2 are activated by the activation signal 180, which has afrequency f1.

As shown in FIG. 8B, in response to the activation signal 180, both EDC150A, in Sector 1, and EDC 150E, in Sector 2, determine the contents oftheir respective EDC-assisted storage locations 145A, 145E and transmitwireless signals representing the contents to the read receiver 195. Thewireless signals may also provide other information, such as, forexample, information indicating the identity (e.g., address or otheridentifying information) or location (e.g., exact or approximate,sector, etc.) of the EDC-assisted storage location 145A, 145E or of theEDC 150A, 150E. EDC 150A transmits the read response signal 185A,representing the contents of EDC-assisted storage location 145A (andpossibly other information), and EDC 150E transmits the read responsesignal 185B, representing the contents of EDC-assisted storage location145E. (As explained previously, the read response signals 185 may reportthe contents of more than one EDC-assisted storage location 145, and/orthey may include other information, such as, for example, informationindicating or allowing the read receiver 195 to determine the locationand/or identity of the EDC(s) 150 and/or the EDC-assisted storagelocations 145.)

The read receiver 195 may be located in or on a slider 525 that fliesover the media, or it may be positioned in a location away from themedia. In embodiments in which the read receiver 195 is located in or onthe slider 525, the read receiver 195 may detect only the desired readresponse signal 185A, or it may detect both the desired read responsesignal 185A and the unwanted read response signal 185B. Similarly, inembodiments in which the read receiver 195 is in a location remote fromthe media, the read receiver 195 may receive both read response signals185A and 185B. The read receiver 195 can apply signal processingtechniques to extract the desired read information (e.g., the contentsof the EDC-assisted storage location 145A) from the aggregate receivedsignal when more than one EDC 150 transmits a read response signal 185.

To assist the read receiver 195 to distinguish between read responsesignals 185 from different EDC 150 and to extract the desiredinformation, the EDC 150 may transmit read response signals 185 thathave different characteristics. For example, referring to FIG. 8B, theread response signal 185A may have a different characteristic (e.g.,frequency, modulation, etc.) than the read response signal 185B. Theread receiver 195 may include or have access to a listing or database ofEDC 150 read response signal 185 characteristics (e.g., a look-up table)and may be capable of configuring itself to receive the target EDC 150'sread response signal 185 (e.g., by tuning its receive circuitry to aparticular frequency, by looking for a particular pattern/modulation,etc.). As just one example, the read receiver 195 may know that EDC 150Aresponds to activation signals 180 having a frequency f1 and transmitsread response signals 185 at a first frequency or with a firstmodulation characteristic, whereas EDC 150E responds to activationsignals 180 having a frequency f1 and transmits read response signals185 at a second frequency or with a second modulation characteristic. Bytuning its receiver to look for read response signals 185 at the firstfrequency or with the first modulation characteristic, the read receiver195 can distinguish the read response signal 185A from the read responsesignal 185B.

FIG. 9 is a block diagram illustrating an EDC 150. To obtain thecontents of one or more EDC-assisted storage locations 145 in anEDC-assisted recording layer 225 of the media, the signal generator 190(or, collectively, multiple ones) of the storage device directs an RFactivation signal 180 having suitable characteristics to activate adesired EDC 150 within the EDC-assisted recording layer 225 toward theEDC 150. The activation signal 180 causes the EDC antenna 152 togenerate power for the EDC's read circuitry 164. The read circuitry 164interrogates one or more EDC-assisted storage locations 145 near the EDC150 and constructs a response signal 185 for wireless transmission tothe read receiver 195.

As explained above, the interrogation mechanisms may be implemented in anumber of ways, including using magneto-resistive sensors used byconventional disk drives adapted for this application. The responsesignal 185 provides information to convey the contents of theinterrogated one or more EDC-assisted storage locations 145. Theresponse signal 185 may also include bits identifying the location(s) ofthe interrogated EDC-assisted storage location(s) 145. For example, theresponse signal 185 may have a format that includes a header identifyingthe address or location of the interrogated EDC-assisted storagelocation(s) 145 and/or activated EDC 150 followed by a body that reportsthe contents of the interrogated EDC-assisted storage location(s) 145.As another example, the response signal 185 may have a format thatitself varies depending on the address or location of the interrogatedEDC-assisted storage location(s) 145 and/or activated EDC 150. Inaddition, or alternatively, the reader may use triangulation techniquesto identify the EDC 150 responding to a read request or to identify thelocations of the EDC-assisted storage location(s) 145 being read. If theEDC 150 transmits a read response signal 185 that includes the contentsof interrogated EDC-assisted storage location(s) 145 that the signalgenerator 190 did not request, the reader may extract or reconstruct(e.g., decode) only the desired information from the response signal185.

Because the EDC 150 transmit the contents of the EDC-assisted storagelocations 145 wirelessly, it is desirable to ensure that the EDC 150respond only to energy from within the data storage device 100. Forexample, the chassis of the data storage device 100 may be shielded toprevent stray activation signals 180 from entering the data storagedevice and read response signals 185 from exiting the data storagedevice 100.

FIG. 10 is a flowchart illustrating an exemplary process 1000 to read anEDC-assisted storage location 145 (or more than one EDC-assisted storagelocation 145) using EDC 150. At 1010, the process begins. At 1020,whether the EDC 150 is energized is determined. If the EDC 150 isenergized, the process proceeds to 1030, where it is determined whetherthe EDC 150 is selected. If so, the process proceeds to 1040, where thecontents of at least one EDC-assisted storage location 145 are sensed,computed, and transmitted.

FIG. 11 illustrates a process 1100 performed by an EDC 150 to read anEDC-assisted storage location 145 (or multiple EDC-assisted storagelocations 145). At 1110, the process begins. At 1120, the EDC 150receives, wirelessly, a read command (e.g., via an activation signal180). The read command instructs the EDC 150 to read one or moreEDC-assisted storage locations 145 and to report the contents. At 1130,the EDC 150 senses one or more EDC-assisted storage locations 145 inresponse to the read command. At 1140, the EDC 150 determines the readresponse signal 185, which reports the contents of the sensed one ormore EDC-assisted storage locations 145. In some embodiments, the readresponse signal 185 may also include information identifying the EDC 150or the sensed EDC-assisted storage location 145. For example, thisinformation may include the location(s) or address(es) of the sensedEDC-assisted storage location(s) 145 and/or the EDC 150. At 1150, theEDC 150 wirelessly transmits the read response signal 185 to the reader.At 1160, the process ends.

FIG. 12 illustrates the use of EDC 150 in the context of reading fromand writing to a hard disk drive 500. FIG. 12 shows the communicationpaths between the read/write circuitry and the EDC 150; the storagelocations are not illustrated at the microscopic level in FIG. 12.

There are many benefits of using EDC 150 to read from a storage media.For example, the use of EDC 150 can eliminate the need for a read headon the slider 525. Furthermore, because, in some embodiments, the EDC150 transmit wireless signals to report the contents of EDC-assistedstorage locations 145, the storage device 100 does not need to spin themedia to read the stored data. In addition, the storage device 100 doesnot need to provide power to EDC-assisted storage locations 145 that arenot being read. Moreover, the use of EDC 150 provides a way to read notonly the conventional recording layer 260, but also the EDC-assistedrecording layer(s) 225 of the media.

Additional Applications

In addition to hard disk drive applications, in which EDC 150 may beadded to a hard disk 520 to increase the data storage capacity of thedisk 520, the techniques disclosed herein may be used advantageously inarchival storage systems. Archival storage systems store data that isnot used often but might need to be accessed in the future, or data thatmust be kept for regulatory compliance purposes. In some embodiments, anarchival storage system uses media with EDC 150 as discussed above.

FIG. 13 illustrates an archival storage system in accordance with someembodiments. In contrast to a hard disk drive, in which the reader andwriter are both within the storage device, the archival storage system'swriter and reader are physically separated. As shown in FIG. 13, thewriter may be incorporated in a first device that accepts a cartridgeinto which a media (e.g., a disk with EDC 150) is inserted. After thedata has been written to the media, the media may be moved to adifferent physical location for storage and, if necessary, reading at alater time. For example, as shown in FIG. 13, the media may be moved toa storage tower in which the media are closely stacked. The storagetower may house hundreds of media. The storage tower includes one ormore readers that, as described above, generate RF activation signals180 having suitable characteristics to activate desired EDC 150 withinthe EDC-assisted recording layers 225 of the media and receive from theEDC 150 the results of the interrogations of the EDC-assisted storagelocations 145 (as described above). Each shelf of the storage tower mayinclude a separate reader (or multiple ones), or a single reader (ormultiple ones collectively) may be capable of reading from media on morethan one shelf. The storage tower may also include a power supplycircuit that provides power (e.g., selectively if the storage towerincludes multiple readers) to individual readers in the storage tower.

The use of EDC 150 in archival storage systems eliminates the need tospin a disk to read archived data. Therefore, less space is required forthe media because there is no need for a conventional read head, slider,or armature. Consequently, large numbers of disks may be stored in closeproximity while still allowing their contents to be read using the EDC150 and the techniques disclosed herein.

It is to be understood that although the archival data storage systemshown and described herein suggests the use of disks with EDC 150, thereis no requirement that the system use media of any particular size orshape. The techniques disclosed herein apply to all media in which EDC150 have been scattered, distributed, embedded, or incorporated. Forexample, the media may have shapes other than round, and they may bethicker or thinner than conventional hard disks.

In the foregoing description and in the accompanying drawings, specificterminology has been set forth to provide a thorough understanding ofthe disclosed embodiments. In some instances, the terminology ordrawings may imply specific details that are not required to practicethe invention.

Although this document explains aspects of certain embodiments in thecontext of data storage devices, using hard disk drives as examples ofdata storage devices, the disclosures herein are not limited to use indata storage device applications. Specifically, the various embodimentsare applicable to other electronic devices storage needs. Furthermore,although certain embodiments are explained in the context of hard diskdrives, and some of the drawings show a hard disk drive as an exampledata storage device, the various embodiments may be applicable to otherdata storage devices such as solid state drives, solid state hybrid diskdrives, optical disk drives, tape drives, and the like.

To avoid obscuring the present disclosure unnecessarily, well-knowncomponents (e.g., of a disk drive) are shown in block diagram formand/or are not discussed in detail or, in some cases, at all.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation, including meanings implied fromthe specification and drawings and meanings understood by those skilledin the art and/or as defined in dictionaries, treatises, etc. As setforth explicitly herein, some terms may not comport with their ordinaryor customary meanings.

As used in the specification, the singular forms “a,” “an” and “the” donot exclude plural referents unless otherwise specified. The word “or”is to be interpreted as inclusive unless otherwise specified. Thus, thephrase “A or B” is to be interpreted as meaning all of the following:“both A and B,” “A but not B,” and “B but not A.” Any use of “and/or”herein does not mean that the word “or” alone connotes exclusivity.

As used herein, phrases of the form “at least one of A, B, and C,” “atleast one of A, B, or C,” “one or more of A, B, or C,” and “one or moreof A, B, and C” are interchangeable, and each encompasses all of thefollowing meanings: “A only,” “B only,” “C only,” “A and B but not C,”“A and C but not B,” “B and C but not A,” and “all of A, B, and C.”

To the extent that the terms “include(s),” “having,” “has,” “with,” andvariants thereof are used in the description, such terms are intended tobe inclusive in a manner similar to the term “comprising,” i.e., meaning“including but not limited to.” The terms “exemplary” and “embodiment”are used to express examples, not preferences or requirements.

The terms “over,” “under,” “between,” and “on” are used herein refer toa relative position of one feature (e.g., a layer of a media) withrespect to other features. For example, one feature disposed “over” or“under” another feature may be directly in contact with the otherfeature or may have intervening material. Moreover, one feature disposed“between” two features may be directly in contact with the two featuresor may have one or more intervening features or materials. In contrast,a first feature “on” a second feature is in contact with that secondfeature.

The drawings are not necessarily to scale, and the dimensions, shapes,and sizes of the features may differ substantially from how they aredepicted in the drawings.

Although specific embodiments have been disclosed, it will be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the disclosure. Forexample, features or aspects of any of the embodiments may be applied,at least where practicable, in combination with any other of theembodiments or in place of counterpart features or aspects thereof.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

We claim: 1-46. (canceled)
 47. A method of using an embeddeddisconnected circuit (EDC) embedded entirely within an EDC layer of amagnetic storage media to read a storage location in a recording layerof the magnetic storage media, the EDC layer being situated above orbelow the recording layer, the EDC being disconnected from the storagelocation, the method comprising: a signal generator transmitting awireless activation signal; the EDC receiving the wireless activationsignal; the EDC determining a contents of the storage location inresponse to receiving the wireless activation signal; and the EDCtransmitting a read response signal indicating the contents of thestorage location.
 48. The method of claim 47, wherein transmitting thewireless activation signal comprises directing the wireless activationsignal toward the EDC.
 49. The method of claim 47, wherein the wirelessactivation signal comprises a read command.
 50. The method of claim 47,further comprising the signal generator configuring an aspect of thewireless activation signal based on an identity of the EDC.
 51. Themethod of claim 50, wherein the aspect of the wireless activation signalis a frequency, a modulation, an amplitude, a duty cycle, or abandwidth.
 52. The method of claim 47, further comprising: the EDCconstructing the read response signal.
 53. The method of claim 52,wherein a format of the read response signal is dependent on one or moreof: an identity of the EDC, an identity of the storage location, alocation of the EDC, or a location of the storage location.
 54. Themethod of claim 47, further comprising: a read receiver receiving theread response signal.
 55. The method of claim 54, wherein the readresponse signal is included in an aggregate received signal, and whereinthe read receiver receiving the read response signal comprises the readreceiver receiving the aggregate received signal, and furthercomprising: the read receiver extracting an indication of the contentsof the storage location from the aggregate received signal.
 56. Themethod of claim 54, further comprising: the read receiver extracting anindication of a location or identity of the storage location from theread response signal.
 57. The method of claim 54, further comprising:the read receiver extracting an indication of a location or identity ofthe EDC from the read response signal.
 58. The method of claim 57,wherein extracting the indication of the location or identity of the EDCcomprises inspecting a header.
 59. The method of claim 57, whereinextracting the indication of the location or identity of the EDCcomprises detecting a format of the read response signal.
 60. The methodof claim 57, wherein extracting the indication of the location oridentity of the EDC comprises using triangulation.
 61. The method ofclaim 54, further comprising the read receiver adjusting a configurationof the read receiver based on a location or identity of the EDC.
 62. Themethod of claim 61, wherein adjusting the configuration of the readreceiver comprises tuning a receive circuitry to a specified frequency.63. The method of claim 61, wherein adjusting the configuration of theread receiver comprises configuring an aspect of the read receiver basedon an expected pattern or modulation characteristic.
 64. The method ofclaim 47, wherein a characteristic of the read response signal providesan indication of one or more of: a location of the storage location, anidentity of the storage location, a location of the EDC, or an identityof the EDC.
 65. The method of claim 64, wherein the characteristic is afrequency.
 66. The method of claim 64, wherein the characteristic is anamplitude, a modulation, a duty cycle, or a bandwidth.